Z9M3 Rear belt Alignment and Tensioner CoreXY

thingiverse

Rear belt Alignment and Tensioner for CoreXY Z9M3 (*OLD) ***Zonestar now includes a metal part for belt alignment. An i have a much smaller belt tension now This is my second type of rear CoreXY belt tensioner. Each belt has its own “Dial It In” Toothed pulleys to loosen or tighten. Along with keeping a single 5m 10mm belt intact to allow for any future ends cuts. I must say, my first test print worked better than I had hoped. This is a multipart module for my Zonestar Z9M3 3-in-1 CoreXY large format FDM printer. I have been modifying my unit and still have many future plans once I find the funds to do so. Working with what I had again, I used 2x 60 toothed pullies. Now that I have test unit made I may be able to use smaller pullies, not a 20 tooth, need more contact space with belt and 3D printed part. Also this is designed for my units 3d printed tolerances. (ABS filament) I’m not using the factory CoreXY layout or belts, I’m using 10mm (really 9mm) steel core belts from amazon. SO.. every brand and type of belt will have different very small changes in thickness. The 3d printed unit must be exact in the space the belt takes up with the pulley. To tight and you will not be able to make changes, any extra may not keep belt compressed on pulley. I included the Sketchup source files along with STL for your customization. Ideally you should be able to make changes and it will hold its place until you secure the 4 screws to lock pulley from spinning once done. SO this is so easy, and with no if any waste of belt. Feed belt trough back of tensioner without pulleys, through the rounded metal spacers on the belt alignment unit then throughout your CoreXY system. Correctly and totally finish Ziptie’n your ends to the front Y carriage, cut any extra unused and properly seat these ends at the front to a completed state. Pull slack belt back though unit until belt tensioner is flush with back of belt alignment module. Pull belts in as much as you can, and make sure belts are placed and correct. Slide in 60 tooth pulleys, leaving one of the nuts showing for tightening, place this screw nut on the 60 toothed in a way that giving slack to belt will rotate pulley, so you can tighten 2nd nut. Thread pulleys with large M5 bolt. I modified an unused (2x) 6mm 20 tooth pully to weld into alignment module. I removed one of the ends washers so that once heated up the teeth will slide into place and weld to plastic to keep from turning. This is the unit that you will tighten once proper tension is reached. Put pulley in way the 2 screws slide into placement, these screws keep the pully from spinning. Once all Parts are installed pull on belts to make tighter. Secure 60 tooth Pulleys to M5 bolts by making the 2 screws very tight. If using thread bolt, try tightening and losing a few times to work out any compression from the M5 bolts threads. Now when you turn the M5 bolt the 60 tooth pulley will also. Now with your hand move the hotend around the bed (should have motor cabled discounted already). Makes sure things move easily. Personally, I like steel cables and things tight, and I Also changed my XY motors to some more powerful and 400 steps. With the unit at the back and center with your hand in the center of the unit as not to favor a side. Move the drive carriage to the very front. With my unit I measure the distance between Y carriage’s and front support on both sides. If the Space is same on both side you’re done, lucky you! Skip to verification steps If not.. Now again with your hand pull on a belt and make it tighten to see one side change in distance. The goal is to only tighten one belt to get alignment, OR both to make belts tighter. Once you know what belt needs tightening, Slowly adjust this single bolt, it will not take much… very little rotation results in major belt changes once belts are near tightness. Move carriage around and re measure, repeat until square. Once things look square to you and even, start measuring and make changes. Then secure modified 20 tooth pully to M5 bolt and the belts will be held in place. (pre torque the 20 tooth into place, so it will not spin in any way once locked to belt pulley M5, print should be tight and not give this pulley room to move) Once all is good Wrap uncut /unused belt around belt tension, tie off with ziptie to secure it. Move carriage around again to make sure things are still square. Print of a skew test to verify if you want, and then tighten belts to correct the print. I did a 250mm x 250mm test and was unable to see any difference that would show unit is out of alignment or askew. The idea is not to modify software or firmware to correct askew alignment. All ya, I’ll also be drilling new cable run mount holes for cable management and to raise to above the new 10mm belt config. (I drilled in wrong place 1st time as seen I picture) Working on smaller version… Will post once designed. Files included Z9 rear belt alignment Z9 rear belt tensioner small test for 20 toothed pulley, if your print is tight and does not move then rest of my prints should be good for you, just have to worry about belt thickness. Sketchup source CAD files for your use Will also need to print or make a higher cable chain support for the rear of the unit, this is the one I made for my 20XX Z9 frame. https://www.thingiverse.com/thing:3052683 Parts List 2x M4 60mm and 2x nuts 2x M4 Spacer 6.33 OD 12.65 L (I have super cheap Caliper, and bought spacer from local hardware store) 2x 60 toothed 5mm bore pully 2x M5 bolt 2X 20 toothed pulley Some washers Enjoy! `mike